When the S7 Edge was released, it came with new Edge features that were not available on the S6 Edge and S6 Edge Plus. However, as soon as they updated those older devices to Android marshmallow, they got the new software features. That's probably how it will be this time. When the other Samsung devices are updated to Android 7.0, they will likely get the new TouchWiz features.

That's what I figured. They'll just wait and do one big update to Nougat for the new features from the Note 7. It makes more sense than doing 2 fairly big updates so close together.